What should stand out for you, instantly, is that the two countries borrow at virtually identical [interest] rates, and have for years.

What this should show to people is that much of the popular stories that people tell about sovereign debt is a myth.

Countries that borrow in their own currencies and can "print" at will don't have default risk, so their borrowing costs are an expression of expectations of future interest rates and growth. The US has been notably profligate since the crisis. The UK (under Cameron) has been prematurely austere. The upshot: it hasn't mattered much on the yield front. [Borrowing rates are the same for the UK with an austerity budge to reduce debt as with the US non-austerity budget and a very high national debtt.]

The fact that the UK borrows so cheaply also undermines the idea that somehow the US' reserve currency status is a big game changer it's not.

If you want to get cute, you can throw in German, Japanese, and Australian rates on their too, all of which have moved similarly, and all of which have pursued different monetary/fiscal approaches.

Trying to tell a good story about why this or that country has low borrowing costs tends to become difficult.

That being said... as Krugman acknowledges, each of these countries has seen interesting currency fluctuations, the more realistic avenue for global markets to express their "vote" on a country's policy.